1. Field the Invention
The present invention relates to an operation microscope having a microscope body, at least one main objective and an illuminating device that includes several optical elements.
2. Relevant Prior Art
Various focusing devices are known for focusing operation microscopes on object details of interest.
For example, focusing can take place by the relative displacement of the whole microscope body inclusive of the main objective along the optical axis. Such an arrangement is described, for example, in Product Information No. 30-259,2-e of Carl Zeiss Company of Germany, the assignee of the present invention. For a required focusing region of several centimeters, however, a device of this kind results in a relatively large constructional volume for the entire operation microscope and a correspondingly costly drive, including gears, for the microscope body proper. Because of the so-called focusing box, which is mounted to the side or behind the microscope body and which accommodates the focusing drive and gears, space is limited for additional accessories, such as secondary viewing devices and documentation devices.
An alternative, second focusing arrangement for operation microscopes takes place in the displacement of the complete main objective along the optical axis, axially of the respective magnification-changing device. Such a device is shown in Product Information 30-001/I-d (pp. 30-31) of the Carl Zeiss Company of Germany. Since the illuminating device that is required is fixed to the microscope body proper, the distance between the boundary surface of the main objective and the illuminating device is changed during focusing. Undesired reflections consequently result. A further disadvantage is that no additional accessories such as micromanipulators for lasers or the like can be attached to the operation microscope.
A third arrangement for focusing an operation microscope takes place by means of a main objective of variable focal intercept, comprised of several individual lens elements that are displacable relative to one another. Such devices are described, for example, in German Patent 2,439,820(U.S. Pat. No. 4,155,622) and in German Utility Model G 9,016,892.5 of the Carl Zeiss Company of Germany. the arrangement of the main objective relative to the illuminating device is a problem here. In a fixed arrangement of the illuminating device in the microscope body, further reflections result from focusing through if the spacing between the main objective and the illuminating device changes. On the other hand, if the illuminating device is uncoupled from the main objective, in that the illuminating beam path is not deflected by the main objective in the direction of the object detail, the problem arises that the whole illumination field is always present, independently of the respective state of focusing. In order to dimension this illumination field optimally for all possible focusing states, a costly illumination device of high light density is required for each case. Coupling the illuminating device to the respective focusing state would also be costly.